Weapons for firing arrows underwater are well known and have been used for many years. Such weapons typically operate on the principle of a crossbow or a sling, and comprise two or more resilient cables attached to a stirrup. The stirrup is pulled rearwardly to tension the cables and is typically held by a trigger. The nock of an arrow is fitted to the stirrup and the arrow is fired by releasing the trigger.
Conventionally-used stirrups comprise a V-shaped stainless steel rod, the tip or apex of which is curved to engage in a nock in the arrow, the end of each arm of the rod being secured to one of the resilient cables.
The most serious disadvantage of conventional stirrups is that they tend to break near the tip after a relatively low number of arrow shots, as a result of repeated bending stresses to which they are subjected. The arms of the stirrup are subjected to forces pulling the arms together when the weapon is loaded, since the cables are then under high tension and exert considerable tensile force parallel to the longitudinal axis of the arrow. Also, the arms are subjected to forces pulling them apart, during loading, when a hunter pulls on the cables near their attachment to the stirrup, so as to tension the cables.
To prevent breaking of the stirrup, it has been proposed to increase the strength of the stirrup arms by increasing their cross-section, but this requires deeper nocks to be formed on the arrows, which prevents the use of thin arrows, which are most efficient in view of the frictional resistance offered to the arrows in flight underwater.
To obviate these disadvantages, I have proposed in my French Patent Application No. 73 04 632 filed on Feb. 9, 1973, to use a stirrup reinforced by a cross bar which is secured to the V arms at its ends, thus giving a practically undeformable A-shaped assembly. This considerably increases the service life of the stirrup.
A stirrup of this kind, however, is unsuitable for certain kinds of weapons, inter alia weapons comprising several, for example two or three, pairs of cables and an equal number of stirrups engaging in a corresponding number of spaced-out nocks on the arrow.
Furthermore, the reinforcing crossbar may cause trouble for some hunters who, during loading, use the arrow as a guide for the stirrup. For this purpose, the cables are stretched while sliding the stirrup over the arrow until it meets the nock. When an A-shaped stirrup is used, the crossbar, rather than the tip or apex of the stirrup, is engaged with the arrow nock.